[plan-i-tair-ee-uh m]
noun, plural plan·e·tar·i·ums, plan·e·tar·i·a [plan-i-tair-ee-uh] /ˌplæn ɪˈtɛər i ə/.
  1. an apparatus or model representing the planetary system.
  2. a device that produces a representation of the heavens by the use of a number of moving projectors.
  3. the building or room in which such a device is housed.

Origin of planetarium

1765–75; < New Latin, noun use of neuter of Latin planētārius planetary; cf. -arium Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for planetarium

Historical Examples of planetarium

British Dictionary definitions for planetarium


noun plural -iums or -ia (-ɪə)
  1. an instrument for simulating the apparent motions of the sun, moon, and planets against a background of stars by projecting images of these bodies onto the inside of a domed ceiling
  2. a building in which such an instrument is housed
  3. a model of the solar system, sometimes mechanized to show the relative motions of the planets
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for planetarium

1734, "orrery," Modern Latin, from Late Latin planeta (see planet) + Latin -arium "a place for." Sense of "device for projecting the night sky onto the interior of a dome" is attested from 1929.

Online Etymology Dictionary, © 2010 Douglas Harper